fn main() {
    let stdin = std::io::read_to_string(std::io::stdin()).unwrap();
    let mut stdin = stdin.split_ascii_whitespace();

    let w: usize = stdin.next().unwrap().parse().unwrap();
    let h: usize = stdin.next().unwrap().parse().unwrap();
    let c: char = stdin.next().unwrap().parse().unwrap();

    println!("{}", output(solve(w, h, c)));
}

fn solve(w: usize, h: usize, c: char) -> Vec<Vec<u8>> {
    (0..h)
        .map(|i| {
            (0..w)
                .map(|j| match ((i & 1) ^ (j & 1) == 1) ^ (c as u8 == b'B') {
                    true => b'B',
                    false => b'W',
                })
                .collect()
        })
        .collect()
}

fn output(ans: Vec<Vec<u8>>) -> String {
    ans.into_iter()
        .map(|x| String::from_utf8(x).unwrap())
        .collect::<Vec<_>>()
        .join("\n")
}